Familiar examples of slides include skis, snowmobile runners, and ice skate blades. However, slides take other forms as well. Even though skis are used extensively herein as examples, it should be understood that much of this discussion applies to other slides as well.
Slides are widely used to assist many types of travel. Such travel may be recreational, as with much alpine and cross-country skiing. Sleds and other slides also provide the best mode of commercial travel in many locations. In addition, slides may prove essential to search and rescue personnel facing emergencies in cold climates.
A slide is typically long and narrow, with a flat running surface, a leading tip, and an upward curve near the leading tip. The running surface may be several inches wide, as with skis, or very narrow, as with ice skates. The upwardly curved portion of the slide is known as the shovel; as used herein, "upward" means away from the snow or other material the slide glides over. Slides range in length from a few inches to many feet. They may be formed of wood, metal, plastic, composite, and other substances. They may be constructed by many methods, such as casting, heat treatment, lamination, and adhesion.
Like many slides, a ski operates by gliding on its running surface over snow or ice. The snow preferably makes initial contact with the ski near the back of the ski's shovel so that the upturned portion of the running surface does not slow the ski by plowing into the snow. Most or all of the running surface is typically in contact with the snow in order to distribute weight to prevent the skier from sinking into the snow.
Skis may be cambered to more evenly distribute their load over the snow. If an unloaded cambered ski is laid on a hard flat floor, only the front and rear of the ski's running surface contact the floor. However, if the cambered ski is loaded with a skier's weight, the ski flattens out so that most or all of the running surface contacts the floor thereby distributing the load across substantially the entire ski. Similar weight distribution occurs as the loaded ski travels over snow and ice.
The speed at which the ski glides over the snow depends on the forces applied to the ski and on the friction between the ski and the snow. In cross-country skiing, friction between the ski and the snow is sometimes desirable, such as when a skier is traveling uphill. Friction may also help reduce speeds to levels that are safe for novice skiers. However, in alpine skiing and many other applications, it is often very desirable to minimize the amount of friction between the slide and the material beneath the slide. Reducing the friction increases the skier's gliding speed because effort that would have gone into overcoming friction is applied instead to moving the ski. Reducing the friction likewise reduces the effort required to ski at a given speed. In short, reducing the friction provides skiers with a range of beneficial choices including increased speed, reduced effort, and combinations thereof.
One known approach to reducing friction is to increase the slide's lubricity. One method of increasing lubricity is to construct the slide from relatively smooth substances. For instance, skis formed of bare metal are generally faster than those formed of bare wood because metal is generally smoother than wood. The running surface of commercially available skis is often formed of polyethylene, polypropylene, or a similar lubricous composition.
Another widely practiced method is to smooth and lubricate the ski's running surface by covering it with a layer of wax. The wax may be applied in several ways. The simplest approach is to rub the wax into the running surface by hand before using the ski. Alternatively, the wax may be melted onto the running surface and then pressed into the surface with a hot iron. Both of these methods have the major drawback that skiing rubs the wax off, so repeated waxing is necessary. In addition, different waxes are optimal for different snow conditions and temperatures. Thus, changes in temperature may make rewaxing desirable even before the previously placed wax wears away.
A related prior approach pumps liquid wax through conduits onto the running surface while the skier skis. However, this approach also has several drawbacks. The wax conduits may break or clog. The wax is not always distributed uniformly over the running surface. The skier must carry a pump which may be bulky, expensive, or vulnerable to extremes of temperature and vibration. The skier must also carry a significant reservoir of appropriate wax; being a liquid, the wax wears away more rapidly than solid waxes. And finally, the skier must continually monitor the rewaxing process.
Another prior approach to reducing friction is to vibrate the ski at ultrasonic frequencies. A major drawback of this approach is the difficulty of manufacturing reliable and economical vibrating skis. In addition, users may be discomforted by the noise or vibrations produced. Vibrating skis may also tend to diminish skier control and may dig into relatively soft snow that conventional skis would rest on or glide over.
Thus, it would be an advancement in the art to provide an apparatus and method for adjusting the friction between a slide and material the slide glides over.
For instance, it would be an advancement to provide an apparatus and method for adjusting the friction between a ski and snow in order to match the frictional drag with skill levels and other conditions.
It would also be an advancement to provide an apparatus and method for reducing the friction between a ski and snow without requiring substantial and repeated intervention from the skier.
It would be a related advancement to provide such an apparatus and method which does not require the repeated application of wax to the ski.
It would also be an advancement to provide a reliable apparatus and method with which skiers may adjust friction between the ski and snow while skiing.
It would be a further advancement in the art to provide an apparatus and method which enhances gliding by reducing friction between the ski and a wide variety of snowy materials.
Such an apparatus and method is disclosed and claimed herein.